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Re: [MEDIACTRL] Control Framework SDP Review - Issue 1

"McGlashan, Scott" <scott.mcglashan@hp.com> Fri, 02 October 2009 11:09 UTC

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From: "McGlashan, Scott" <scott.mcglashan@hp.com>
To: Chris Boulton <chris@ns-technologies.com>, "mediactrl@ietf.org" <mediactrl@ietf.org>
Date: Fri, 02 Oct 2009 11:09:59 +0000
Thread-Topic: [MEDIACTRL] Control Framework SDP Review - Issue 1
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Subject: Re: [MEDIACTRL] Control Framework SDP Review - Issue 1
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Seems a reasonable change to me. 

Scott


-----Original Message-----
From: mediactrl-bounces@ietf.org [mailto:mediactrl-bounces@ietf.org] On Behalf Of Chris Boulton
Sent: Friday, October 02, 2009 12:53
To: mediactrl@ietf.org
Subject: [MEDIACTRL] Control Framework SDP Review - Issue 1

Jonathan Lennox has kindly provided expert SDP review for the Media Control Channel Framework document.  This is the first in a series of emails intended to address the points raised.  At this final stage your input is extremely important.


My first comment is on the use of the values "TCP/CFW", "TCP/TLS/CFW", "SCTP/CFW" and "SCTP/TLS/CFW" for the SDP <proto> field, with a "fmt"
field of "*".  A more usual use of the proto field would be to use the existing proto fields "TCP", "TCP/TLS", "SCTP", or "SCTP/DTLS", and then (after defining "application/cfw" as a media type) use "cfw" as the <fmt> field.

Thus, instead of having

m=application 7575 TCP/CFW *

you'd have

m=application 7575 TCP cfw

This has the advantage of leveraging other existing work in SDP, e.g.
you would get ICE-TCP "for free" once it's finished.


To be sure, there would be some disadvantages of this.

Notably, "SCTP" and "SCTP/DTLS" are still only defined in an individual I-D, and there's been only limited attention paid to it in the MMUSIC community.  On the other hand, if Mediactrl has the expertise to understand how SCTP should work in a comedia context, it'd probably be better to let this be available to everything that would want to use it, rather than just CFW.

[Chris] I agreed that the proposed change is more elegant and if it means that we get ICE-TCP for free then its a bonus.  It is  the recommendation of the authors that this change is made to the draft.  Any comments or objections?

--
Chris Boulton
CTO & Co-founder
NS-Technologies <http://www.ns-technologies.com>
m: +44.7876.476681
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